Continuous motion packaging machines used to package articles such as beverage containers include numerous workstations, such as those which either manipulate a carton blank, group a selected numbers of articles or place the articles into fully formed cartons. Such packaging machines are well known, and typically include a carton feeder having a magazine which delivers carton blanks to a selecting device that continuously selects cartons one at a time from the magazine and delivers the selected cartons to a packaging machine conveyor. The magazine and the selecting device, or selector, collectively comprise the carton feeder, such as rotary feeders and segmented wheel feeders. The magazine delivers the cartons to the selector either by gravity or by way of a magazine conveyor, such as a chain conveyor, or by using a combination of gravity feed and a magazine conveyor. The packaging machine conveyor transports the selected carton to the next workstation, where the carton is manipulated in preparation for holding the articles.
Known selector assemblies may include reciprocating levers which Position a vacuum cup to contact the front surface of the leading carton in the magazine, and pull at least a portion of that carton from the magazine, at which point it is engaged by a wheel for delivery to a conveying assembly, such as opposed nip rollers. These known systems are used in segmented wheel feeders, such as those disclosed in U.S. Pat. No. 4,034,658 to Sherman and U.S. Pat. No. 4,709,538 to Olsen, Jr. et al. Specifically, known segmented wheel feeders include a selector including a vacuum assembly and a picking assembly having a lever arm and supporting a vacuum cup to contact the leading carton or carton blank in the magazine. The top edge of the loading Carton is pulled by the picking assembly below an upper retaining clip, and moved in a downstream direction. A rotating segmented wheel, that is a split-type wheel defining one or more cut out portions to form segments, turns toward the carton selection zone and the leading carton. The segments of the rotating wheel or wheels contact the carton, and cause the carton to move between the periphery of the segmented wheel and the periphery of an adjacent nip roller. Further rotation of the segmented wheel pulls the carton fully out of the magazine and downstream of the segmented wheel and nip roller to a further conveying device, such as additional nip rollers and/or belt or chain conveyors. The carton then is moved further downstream to the next carton workstation where the carton blank may be positioned for wrapping around a preformed bottle group or, in the case of a collapsed basket-type or sleeve-type carton blank, manipulated into an opened position for receiving the articles.
Packaging machine productivity commonly is measured by the number of fully packaged cartons containing a particular article group configuration processed through the machine per minute. Additionally, many packaging machines are capable of being configured to package different article configurations, which can increase or decrease the number of article groups packaged per minute. Other advances in the various workstations of packaging machines have increased the speed and efficiency at which the cartons are manipulated, the articles are arranged into groups and placed into the carton, and in fully enclosing certain types of cartons around the articles.
Increased or decreased packaging machine speed necessitates that components be operated faster or slower to match the speed change, which can require that some operations be initiated at different cycle positions. For example, it is known that vacuum valves controlling delivery of vacuum in feeders can be advanced or retarded to cause the vacuum delivery to reach the vacuum cup at the same feeder position, regardless of the carton feeder or carton opener speed. One known adjustable valve includes a disk with an arcuate slot contacting an adjacent disk with spaced ports. The rotational position of the slotted disk with respect to the ported disk can be changed selectively to alter the timing of the vacuum and pressurized air cycles. In another packaging machine operation, that is the carton closing workstation in certain types of packaging machines, the apparatus which delivers glue to a carton flap prior to folding mating flaps together can be controlled using a programmable limit switch/encoder assembly. As the encoder detects a change in machine speed, which can be a function of the position of a selected packaging machine component, the limit switch operates to control the timing of glue delivery to "match" machine speed.
As the packaging operations of the entire process increase in speed, the carton feeder also must deliver the cartons to the downstream workstations of the packaging machine at a matching rate. Known, high speed carton feeders can deliver certain types of cartons efficiently at rates up to approximately 300 cartons per minute, with the most common beverage container packaging machine speed presently operating in the range of approximately 150-300 cartons per minute. With increased machine speeds, however, problems can arise in carton feeding. As machine speeds approach 300 cartons per minute, the efficiency of known, high speed carton feeders decreases. For example, there is an increased risk of the picking assembly's failing properly to remove a carton from the magazine, or failing to release the carton from the vacuum cups at the appropriate position. These occurrences can lead to additional problems, including machine jams and increased vacuum cup wear. Further, it is recognized that cartons which have become warped due to storage conditions but which are otherwise suitable for packaging articles are more difficult to remove from the magazine, especially at higher speeds. This difficulty also can exist particularly with respect to certain types of cartons, such as wrap-type cartons which include numerous performed design cuts and surfaces. Also cartons which have inconsistent varnish application tend to adhere to one another when loaded in the magazine, and can be difficult to select.
As known carton feeders have increased in speed, it has been found advantageous to use pressurized air to cause the carton to be efficiently released from the vacuum cups at the correct feeder position. The use of pressurized air in addition to the vacuum used to pull the carton from the magazine, especially at high machine speeds, presents additional challenges relating to delivering the vacuum to the vacuum cups at the precise moment the vacuum cups contact the carton, while also delivering pressurized air to the cups at the precise feeder position at which the cups must release the carton.